[PATCH] D150706: [LAA] Update MaxSafeDepDistBytes when non-unit stride

[Michael Maitland via Phabricator via llvm-commits]

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MaxSafeDepDistBytes must be updated according to the stride
of the loop, otherwise it is possible that the value is
not conservative enough. For example:

  for (int k = 0; k < len; k+=3) {
    a[k] = a[k+4];
    a[k+2] = a[k+6];
  }

has MaxSafeDepDistBytes=8. However, if we do not use the stride
in the calculation, we incorrectly compute MaxSafeDepDistBytes=24.

This change is related to 682cfc1, however, that change did not
go far enough and set MaxSafeDepDistBytes according to stride.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D150706

Files:
  llvm/lib/Analysis/LoopAccessAnalysis.cpp
  llvm/test/Analysis/LoopAccessAnalysis/depend_diff_types.ll
  llvm/test/Analysis/LoopAccessAnalysis/depend_diff_types_opaque_ptr.ll
  llvm/test/Analysis/LoopAccessAnalysis/max_safe_dep_dist_non_unit_stride.ll

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